**Answer:**

A chopper is an electronic device that converts a constant voltage DC (Direct Current) into a variable voltage DC directly. It is a type of DC-to-DC converter that operates by switching the input voltage on and off at a high frequency. This switching action allows the chopper to regulate the output voltage by controlling the duty cycle of the switch.

**Working Principle of a Chopper:**

A chopper consists of a power semiconductor switch (usually a transistor or an IGBT), a diode, an inductor, and a load. The power switch and the diode are connected in series with the input voltage source, while the inductor and the load are connected in parallel.

The chopper operates in the following manner:

1. **Step 1: ON-State:** When the power switch is turned on, the input voltage is connected to the load through the inductor. The current through the inductor increases linearly, storing energy in the magnetic field.

2. **Step 2: OFF-State:** When the power switch is turned off, the diode becomes forward biased. The inductor discharges its stored energy into the load, causing the current to continue flowing. However, since the power switch is open, the voltage across the load decreases.

3. **Step 3: Repetition:** The ON and OFF states of the chopper are repeated at a high frequency, typically in the range of tens to hundreds of kilohertz. By controlling the duty cycle (the ratio of ON-time to the total period), the average output voltage can be varied.

**Advantages of a Chopper:**

- The chopper provides efficient power conversion with low power losses.
- It enables the control of output voltage in a wide range.
- The chopper can provide both step-up and step-down voltage conversion.
- It allows for regenerative braking, where the energy stored in the load's inductance can be transferred back to the source.

**Conclusion:**

In summary, a chopper is an electrical device that converts a constant voltage DC into a variable voltage DC directly. It achieves this by switching the input voltage on and off at a high frequency and controlling the duty cycle of the switch to regulate the output voltage. This makes the chopper a versatile and efficient DC-to-DC converter widely used in various applications, including motor drives, power supplies, and renewable energy systems.